Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$96.61	11.386%	$107.61	$107.61	$107.60	$107.60
Purchase #2	$149.65	8.576%	$162.484	$162.48	$162.50	$162.50
Purchase #3	$166.82	11.199%	$185.5022	$185.50	$185.50	$185.50
Purchase #4	$185.81	5.556%	$196.1336	$196.13	$196.15	$196.10
Purchase #5	$120.78	12.784%	$136.2205	$136.22	$136.20	$136.20
Purchase #6	$127.51	10.395%	$140.7647	$140.76	$140.75	$140.80
Purchase #7	$249.34	13.718%	$283.5445	$283.54	$283.55	$283.50
7 purchase totals =	$1,096.52		$1,212.2595	$1,212.24	$1,212.25	$1,212.20